This invention relates generally to apparatus for handling, sorting and testing electronic devices. More specifically, it relates to an apparatus for testing a wide range of radial lead devices and featuring a probe assembly with a self contained drive train, adjustable contactor assemblies, and a linear shuttle that carries the devices in a cycled pick and place motion through a series of test stations.
In the manufacture of electronic devices it is necessary to test the devices and sort them according to whether they are defective or according to the value of some parameter. The sorted devices are collected in bins. Production economics require that these testing, sorting and collecting operations be very rapid, reliable and without significant interruption.
The design of the handling and sorting apparatus must take into account the type of device being processed. Devices generally fall into one of three categories, integrated circuits having two parallel rows of leads, axial lead devices such as resistors and diodes, and radial lead devices such as signal and power transistors. Radial lead devices have a body and a set of leads, typically three or four, which extend from the body in generally the same direction.
Radial lead devices present several handling problems. First, their overall geometry is less conductive to automated handling than other more compact or more symmetrical devices. Second, their leads, particularly those of certain commonly used signal transistors, are often narrow wires that are easily bent. The apparatus must therefore be able to reject devices with badly bent leads and test properly configured devices without bending the leads or causing them to contact one another during testing. It is also preferable that the apparatus be capable of straightening leads of devices that are slightly bent. Another difficulty is that the reliability of the test is directly related to the ability of the test system to remove an oxide surface coating that builds up on the device leads. A known solution is to "wipe" or scrape the contacts over the leads before testing. This is clearly a more difficult mechanical problem when the leads are fine wires.
Apparatus capable of handling these devices are known in the prior art. The present assignee, for example, manufactures transistor sorters and testers under the trade designations Type 830 and Type 1635. Typical continuous operating speeds of these units are 4,000 and 5,600 transistors per hour, respectively. While these units function well, they have a disadvantage in that they accept a limited range of devices. The Type 830 sorter processes only small signal transistors having generally cylindrical, "can" bodies. The Type 1635 sorter accepts "can" body signal transistors as well as molded power transistors and signal transistors with non-cylindrical bodies. However, to process these different types of devices, the sorter must be broken down and reassembled with different handling components and test probes. The conversion components are costly and the conversion operation requires as much as an hour to complete.
To wipe the leads, the Type 830 sorter utilizes a "side entry" feed where the leads are moved into a sliding engagement with the contacts. This contactor arrangement also performs a certain degree of lead combing. The Type 1635, while in general more versatile than the Type 830, does not provide lead straightening. Also, the wiping action is frequently developed by a flexure of the test contacts as they are lowered onto the leads. This method of developing a wiping action can be effective, but because the contacts move in substantially one direction they develop only a comparatively small wiping movement of the contact tip on the lead. Also, with fine wire leads such a system must also include an arrangement for supporting the leads against the lateral force of the contacts.
In use on a production line for electronic equipment, it is very desirable to be able to switch from processing one type of radial lead device to the processing of another type depending on production requirements. More generally, it is very desirable to have one test handler/sorter which can quickly and reliably test any of a wide range of devices. The range should include comparatively large heavy molded power transistor with strip leads either aligned in a row or in a triangular array, small signal transistors with cylindrical bodies and long or short wire leads in a triangular array, and any of the other common types of devices such as those with semi-cylindrical bodies. No known sorting and testing apparatus can readily convert to process all of these devices.
It is therefore a principal object of the invention to provide an apparatus for handling and testing radial lead devices that quickly and easily converts to accept devices having a wide range of configurations, masses, and lead types.
Another object of the invention is to provide an apparatus with the foregoing advantages that drives its contacts in a motion that includes an effective wiping action that ensures a reliable electrical connection, and in the case of fine wire leads, can comb them.
Another principal object of the invention is to provide a handling system that reliably and quickly carries the devices through a series of test stations and positions then accurately at each test station for testing and other processing.
A further object is to provide an apparatus with the foregoing advantages where the contacts can also be adjusted longitudinally, laterally and vertically with respect to the leads of a device positioned at a teat site.
Another object is to provide an apparatus which allows the replacement of component such as the handling system and probe assembly with no loss of synchronization between these assemblies.
Yet another object is to provide an apparatus where the entire contactor assembly is easily and quickly replaced.
Still another object is to provide an apparatus with the foregoing advantages that has a high operating speed, is dependable, and does not require close supervision.